The present disclosure relates to a method of manufacturing a patterned substrate and a method of manufacturing a semiconductor device using the same.
Semiconductor light emitting elements are widely used for light sources of various kinds of lighting devices. A semiconductor light emitting element includes a substrate and a semiconductor layer epitaxially-grown on the substrate.
Light generated in the semiconductor layer is emitted from a substrate-side or from the semiconductor layer located opposite to the substrate-side.
In the case in which the semiconductor light emitting element is a gallium nitride-based semiconductor element, the semiconductor layer has a high refractive index. Accordingly, total reflection tends to occur due to a high difference between a refractive index of the semiconductor layer and a refractive index of the air or the like surrounding the semiconductor light emitting element, so that light is less easily extracted to an outside of the semiconductor light emitting element. Therefore, the semiconductor light emitting element including such a semiconductor light emitting layer has room for improvement in light extraction efficiency.
As a method for improving light extraction efficiency, a technique is known in which a plurality of protruding portions (which may be referred to as “irregularities” in some documents) are formed at a surface of a substrate on which a semiconductor layer is to be epitaxially grown to scatter light emitted from the semiconductor layer on the surface of the substrate, which allows light at an incident angle smaller than the critical angle of total reflection to be emitted toward the outside. For example, such a sapphire substrate with a plurality of protruding portions is called as a “Patterned Sapphire Substrate (PSS)”. JP 2012-64902 describes an example of a method of manufacturing a semiconductor substrate in which distortion of a pattern of irregularities is reduced.